This invention relates to the field of integrated circuits. More particularly this invention relates to increasing the thermal dissipation capacity of integrated circuit packages.
Integrated circuits, specifically monolithic integrated circuits, are typically packaged prior to use. The package provides a variety of benefits for the use of the integrated circuit. For example, the package tends to protect the integrated circuit from physical damage, such as chemical damage that may result from contact between the integrated circuit and materials in a corrosive environment, or mechanical damage that may result from the integrated circuit being forcefully contacted during shipping, use, or other handling.
The package for an integrated circuit may also provide the additional benefit of making electrical contact to the integrated circuit much easier to accomplish. This is generally done by providing electrical continuity between the very small and closely spaced electrical contacts on the integrated circuit and relatively larger and farther spaced electrical contacts on the outside of the package.
As integrated circuits operate, they tend to consume an amount of electricity that is used to operate the various electrical components of the integrated circuit. As the speed of integrated circuits increases, so also does the amount of electricity which they consume increase. The electricity consumed by an integrated circuit tends to be predominantly discarded as heat. Thus, as the speed of integrated circuits has increased, so to has the amount of heat which the integrated circuits produce increased.
Some integrated circuit manufacturing methods use molds to form the integrated circuit packages. The protective coatings of the package typically completely encompass the integrated circuit, wire bonds, and electrical contacts of the integrated circuit carrier or substrate. Unfortunately, the protective coatings also tend to function as an insulating layer, and may substantially impede thermal dissipation from the integrated circuit. Thus, the heat dissipation of such integrated circuit packages is degraded due to the configuration of the protective coatings of the package.
What is needed therefore, is system for protecting the sensitive components of the integrated circuit package without unduly impeding the heat dissipation capacity of the integrated circuit package.
The above and other needs are provided by a mold for use in encapsulating an integrated circuit, wherein an encapsulant is injected into the mold during the manufacture of the integrated circuit. The improvement to the mold is a shaped member having an abutting surface for contacting a surface of the integrated circuit and thereby substantially preventing encapsulant from adhering to the surface of the integrated circuit, whereby the surface of the integrated circuit is left exposed.
Because the surface of the integrated circuit is left exposed, the encapsulant used to encapsulate the integrated circuit does not form a thermal barrier between the integrated circuit and the exterior of the package. Thus, the packaged integrated circuit is able to more efficiently conduct heat away from the integrated circuit.
In various preferred embodiments, only a portion of the surface of the integrated circuit is left exposed. Most preferably, any electrical connections on the surface of the integrated circuit are sealed within the encapsulant and not left exposed. The shaped member may be either an integral part of the mold, or a mold insert. In a most preferred embodiment the shaped member is formed of silicone.
In another aspect, the invention includes an integrated circuit packaged in an encapsulant, where the improvement is a void formed in the encapsulant, whereby at least a portion of a surface of the integrated circuit is exposed through the void in the encapsulant. In various embodiments, the integrated circuit may be either a flip-chip or a wire bonded chip. Further, a thermally conductive material may be disposed within the void formed within the encapsulant. The thermally conductive material preferably forms a heat conduction path to conduct heat away from the integrated circuit. In a most preferred embodiment, a heat sink is disposed adjacent the thermally conductive material. The heat sink absorbs and dissipates the heat conducted through the thermally conductive material.
In yet another aspect, the invention includes a method of packaging an integrated circuit in an encapsulant, where the improvement is the step of forming a void in the encapsulant, whereby at least a portion of a surface of the integrated circuit is exposed through the void formed in the encapsulant.